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48 Cards in this Set
- Front
- Back
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BOP - Electrical System Purpose |
Has No Safety Related Functions, and no credit is taken for the offsite power sources for Safe Shutdown due to appendix R or Station blackout. Non-Safety Related functions are:
1. Connect the main generator output to the AEP System Grid 2. Supply Power to all plant electrical buses including the RCP Buses, 600 VAC BMC AND CMC. Uses an offsite power source when the unit is offline. 3. Supply power for support building and functions. |
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U2 765 kV Breakers (A1, A2) Operation Control Switches Control Power |
Dead Tank Breaker - SF6 - Quiet Operation
Hydraulic Oil is used to close and open breaker. Pump is used to charge system with Hydraulic fluid. Loss of hydraulic fluid prevents open/closing of breakers and an alarm actuates in switchyard.
C/S in switchyard and in U2 CR must have close red target flag to close breaker. Generator lockout relays must be reset.
Control Power - 2 redundant 125 VDC batteries in 765 kV control house. Loss of batteries will prevent tripping or closing the breakers
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U1 345 kV Breakers (O, O1) Operation Control Switches Control Power |
Dead Tank Breaker - SF6 - Quiet Operation
Air is used to operated breakers. Compressor charges breakers. Loss of Air will prevent open/close operation of breaker and alarm will actuate in switchyard.
C/S in switchyard and U1 control room must have red target to close. Generator Lockout relay also must be reset.
Control power comes from 2 125 VDC batteries in the 345 kV Control House. Loss of the batteries will prevent closing or tripping of the breakers. |
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Reserve Power Breakers 34.5 kV ( BE, BC) Operation Control Power |
Oil Quenched
Compressed air to operate breaker. Loss of air pressure will prevent breaker operation.
Control Power is provided by 125VDC battery in control house. Loss of control power prevents remote operation of breaker.
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Reserve Power Breakers 34.5 kV (BE) FUTURE Operation Control Power |
SF6 Dead Tank Breaker
Springs that are charged by 125VDC motor.
Loss of SF6 gas will lockout breaker.
Control Power is provided by the 125 VDC battery in 345 kV control house. |
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Reserve Power Breakers 34.5 kV (BD) Operate Control Power
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SF6 - Dead Tank
Air pressure to operate
Control power is from 125 VDC in the 345 kV control house battery. |
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Reserve Power Breakers 34.5 kV (12AB, 12CD) Operate Control Power |
Oil Quenched
Compresses Air
Control Switches in U1, U2 and 345 kV control house. All targets must be red for breaker to close
Control power from 345 kV 125VDC |
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Supplemental Diesel Generator output Breakers and Tie Breaker |
Control Power is 48 VDC provides power to the trip coil. 230VAC is power to the breaker closing coil. |
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Supplemental Power Supply System |
This is the 125 VDC Distribution System
Two Separate Systems. 1 345 kV Switchyard, 2 765 kV Switchyard.
Provides control, indication, and protection system power. To:
1. All 765 kV and 345 kV circuit breakers 2. All 34.5 kV circuit breakers ( from the 345 kV switchyard) 3. Motor Operated Air Breaker (MOAB) U andV 4. Protection and Control Power for TR-4 and TR-5
Loss of 125VDC is a loss of control and protection for switchyard breakers and loss of the ability to open or close circuit breakers. Indication is in the Control Room.
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1EP U1 Breaker, 2EP U2 Breaker |
Control Power is 48VDC in the SDG switchgear enclosure. (Wet Cell Battery with charger/conditioner) |
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Switchyard 115 VAC-230 VAC |
Provides Freeze protection for circuit breakers, MOAB switches and relay cabinets.
Provides power for the air compressors and hydraulic pumps which provide pressurized oil and air to operate breakers.
Provides power for TR-4 and TR-5 Cooling -loss of cooling to TR-4 results in automatic, time-delayed trip of TR-4. -loss of cooling to TR-5 restricts it to 90 MVA- sufficient for reserve feed requiremnts. |
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EP Yard 48 VDC Distribution |
Power to MOAV switches X1 and X2 4kV circuit breakers 1EP and 2EP Transformers 12-EP1 and 12-EP2 SDG Outputbreakers & Tie breaker - Trip coil 48 VDC, closing coil 230VAC
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U1 Main GSU |
345kV/26kV Three Phases Rating 1300MVA Grounded Wye to Delta Severon Monitors oil dcomposition production that would occur if oil was overheated caused by insulation degradation, highloading, loss of cooling, fault currents. -> High Winding Temperatures. - Powered from 1-TSCN-3 (11C9)
Cooling is Forced Oil to Air (FOA) Each Oil cooler is 1 heat exchanger, 1 pump, and 3 fans. 5 Oil Coolers in two Groups -Group 1 is in Continous or RUN (1,3,5) -Group 2 is in AUTO and cycles on temperature (2,4) on 70C
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U1 Main GSU Cooling Power |
600 V breakers chich supply cooling are Load Shed for Train A.
Cooler Power supplies -Group1 Normal: 11C9 to 1-TCSN-3 Alternate: 11D9 to 1-TCSE-3 -Group2 Normal: 11D9 to 1-TCSE-3 Alternate: 11C9 to 1-TCSN-3
NORMAL POWER LOSS If Run Group, then will restart after 20 seconds If AUTO Group, then set point is 75C When power is restored the group will repower from normal source.
Reduced or Loss of Cooling -May continue operation with few than 5 coolers. Must lower load appropriately.
With Loss of all power, must reduce to 50% with Rapid Power Reduction. If cooling cannot restored within 2 hours then trip.
If winding temperature Hi-Hi is received accompanying loss of cooling power -> trip
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U1 Main GSU Supplemental Cooling |
Temp. MOD. Used to clear high oil temperature alarm.
Uses Two spray headers to provide demineralized water 38 gpm to cool transformer.
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U2 Main GSU |
765kV/24.63 kV Phases 1 ( 3 separate transformers) Rating 500 MVA/phase
Cooling is Forced Oil to Air 5 Oil Coolers (1 heat exchanger, oil pump, 3 fans)
2 Groups -Group 1 is Continuous (1&5) -Group 2 cycles (3&4) -Cooler 2 is a backup operated manually
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U2 Main GSU Cooling Power |
Cooler Power supplies -Group1 Normal: 21C9 to 2-TCSN Alternate: 21D9 to 2-TCSE -Group2 Normal: 21D9 to 2-TCSE Alternate: 21C9 to 2-TCSN
When Normal Out of Service - will run continuously on other power source.
Will shed on 600 VAC Train A
Requires 2 groups of coolers available to energize transformer. Reduction in load with coolers out of service.
Loss of Cooling - Restore Coolers immediately or TRIP
Coil Temperature High (105C), Oil Temperature High (90C) - provide more cooling, reduce load in 10% increments and revaluate temperature.
Coil Temperature High-High (120C) -Rapid reduce power to 50% power, continues to rise, trip.
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Tr-4 |
HV/LV (345kV and 765kV)/ 34.5 kV Supply to Train A Reserve power from 345 kV Bus 1 and 765 kV Bus 2 Phases 1 Rating 500 MVA/phase auto transformer 115MVA / phase tertiary
Cooling is FOA
Protection: -Overcurrent -Transformer Differential Current -Sudden Pressure -Ground Fault -Gas Detector
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Tr-5 |
345 kV/34.5kV Train B 3 phases
Cooling: OA/FOA/FOA Rating: 90/120/150 MVA (depends on cooling mode)
Protection Relays: -Overcurrent -Transformer Differential -Sudden Pressure -Ground Fault -Gas detector |
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Reserve Auxiliary Transformers |
TR101AB, TR101CD, TR201AB, TR201CD 34.5kV/4.16kV Cooling OA/FA/FA Rating 18/224/30 MVA
Supply RCP buses during plant startup/shutdown Has: Load Tap Changing Transformer
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Load Tap Changing Transformers (LTC)
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-Allows voltage of safety buses to be near analytical value) -High voltage can cause accelerated equipment aging, Low Voltage results in high currents, which can prevent critical loads from starting or continuing to run. -Must be in AUTO in Modes 1-4 to be operable
Senses output voltage and maintains at (knows if loaded by position of reserve feed breaker) -4171 volts loaded (119.2V indicated) -4635 volts unloaded (132.4 V indicated)
Operation -senses greater than 41 volts (1.2 volts indicated) changer waits 5 seconds for any change. No Change then tap changer adjusts up or down one tap (41 volts)
During the process of changing taps, power is maintained by closing a set of contacts that bypass the tap contacts. Once the bypass contact closes, the tap changer motor drives the selector switch to the next contact. The bypass contact reopens to complete the operation. During tap changes, a vacuum is drawn on the tap contact to prevent arcing.
LTC power supply is normal seeking and will automatically transfer through break before make circuit to backup source
The power supply of the Load Tap Changers is from 1-11D or 2-21-D9 through TCSE and will transfer to backup power source (step down transformer supplying control power from 34.5 kV Side)
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Reserve Auxiliary Transformers Cooling |
8 Coolers: Each has one radiator and 4 fans 2 groups that operate in Auto -Group 1 Winding temperature of 80C -Group 2 Winding Temperature of 85C
Normal U1 11D9, U2 21D9. Backup is stepdown transformer upstream of RAT
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Reserve Auxiliary Transformer Protective Relays |
-Transformer differential -Sudden Pressure -Transformer Overload -Bus overload -Ground Fault |
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Unit Auxiliary Transformers |
26kV Isophase to 4.16 kV to supply RCP Bus when unit is online
3 phases
Cooling OA/FOA/FOA Rating 18/24/30
Two Coolers one oil pump to 4 fans
Power supply is U1 11C9, U2 21C9
Protective Relays -Differential -Sudden Pressure -Transformer Overload -Bus overload Ground Faults |
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BOP 600V Transformers |
4kV/ 600VAC TR-11BMC, TR-11CMC, TR-21BMC, TR-21CMC
3 phases
Dry/Air cooled by 12 cooling fans controlled locally
Protection Relay -Differential -Overcurrent -4kV ground fault
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TR-12EP-1 |
69 kV/4kV Common EP Bus Regulated output for varied inout voltages Required for AOPS to be operable Rating 7500 kVA Phases 3 Cooling OA EP is 30 degrees out of phase with other AC Sources. Designed to handle an accident in one unit, containment spray with blackout. |
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TR-12-EP2 |
Identical to TR-12EP1, Can be used if a normally open disconnect is closed.
Supplies visitor center,plant security, streetlights. -SDG cannot sense voltage on this line and would NOT start
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Supplemental Diesels |
TRM Equipment and not safety related (Available NOT Operable)
Auto Start on loss of 4kV to common EP bus.
Each is sized to 2250 kW (4500 kW total)
Have the Capacity to power at least one train of vital equipment needed to ensure RCS inventory control following a SBO and failure of the operable EDG for 24 hours. -MDAFP, RHR Pump, and a bank of pressurizer heaters.
Can support bot DIS trains
Overall Core Damage PRA reduction of 20-30%
Can start and come up to speed in 10 secs, but is set at 25seconds for less wear.
Inventory Control, One train of ESW, CCW, and CCP. It can also support a NESW pump with A control air compressor so charging and let down can be restored.
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EP response to Station Blackout (SBO) |
-SDG's PowerLynx system sense undervoltage on the 69 kV EP bus, waits 150 seconds.
-Sends Open signal to the Motorized Disconnect Switch (MDS)
-Verifies the MDS Open and then sends the start signal to the SDGs
-1st SDG to reach speed and voltage closes its breaker (25 seconds) onto the dead bus.
-2nd SDG auto synchronizes to the bus and closes its output breaker.
-PowerLynx then closes the 52T1 tie breaker to station EP Bus
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SDG Surveillances |
Bi Weekly - run unloaded to keep engine lubricated. Check RPMS and Voltage
Quarterly - Loaded run. Diesel comes up to speed and closes breaker, 2nd diesel syncs to first and closes breaker. Tie breaker is closed to EP.
18 Month Surveillance - Simulated Emergency Start by a simulated undervoltage signal that opens up the disconnect and starts the sequence. |
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Degraded Bus Voltage (Why?) |
Provide auto separation of safety buses from the grid when offsite power is insufficiently stable to allow safe unit operation.
Could result in failure of safety related loads to position/start because of blown fuses.
Could result in started loads tripping due to overload trips resulting from high current at low voltage. |
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Undervoltage |
3 sensors per T bus
2/3 (U1 94V, U2 93V) below for 2 seconds will energize load shed relays, which starts the associated diesel. |
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Degraded Bus |
Provides Auto Separation of the safety busses (Opens RCP Breaker Tie to 4kV safety busses) from the grid when offsite power is insufficiently stable to allow safe unit operation.
3 sensors per pump bus for each train (T11A/T21A or T11D/T21D)
Low voltage sustained for 120 seconds on pump bus. (NO SI Signal OR SG Low-Low (U1 5%, U2 22%))
Low voltage sustained for 9 seconds (WITH SI Signal OR SG LOW-LOW)
If on Auxiliary Feed Transformers -Stand for 90 seconds RCP buses will fast transfer to Reserve Feed. -RAT will step load change to address the DBV condition. -RATs have 21 seconds to clear DBV condition. (9 seconds time delay to get DBV, 90 seconds wait to goto RATs, 21 seconds for RATS to correct = 120 second actuation.)
Opens that trains RCP Bus Tie Breakers to T Bus for any T Bus that has: -Degraded voltage sense on its associated pump bus (t21A or T21D) |
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Emergency Power |
"Alternate Offsite Power" 69 kV from Dumont or Bridgman
EP is 30 degrees out of phase with other grid connections through reserve power an unit auxiliaries.
-EP breakers are interlocked to prevent closure unless all other feed breakers to that bus are open. "Dead Bus to close breaker AND must be removed before connecting any other AC Source.
-Sized to handle a single unit blackout and containment spray and black out only on the other unit.
-600 amp limit due to aluminum cables
-THE EP Feed breaker to a T Bus must be manually closed to supply power. Interlocked with all ofther feed breakers to T-bus must be open due to 30 degrees phase difference. |
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Backfeed |
Allowed in Only Modes 5 & 6. Cannot be credited even then as a TS source of power. Grid connection is through one or both output breakers (prefer both to prevent disruption)
Need to remove Generator disconnect links to isolate main generator from GSU (this isolated U1 Ground protection on generator so isophase bus ground installed for backfeed)
Auto-transfer to the RATs will occur for faults in the main transformer.
U1 (O, O1 Closed) ( Was K1, K, K2)
U2 ( A1, A2, B all closed) (A2 open will leave unit venerable to fault on Dumont line.
Interlocks: Unit and Overall Differential Lockout Relays (HEA) rest to allow generator ouput breaker closure. When closing the first generator output relay, the "backfeed relays" behind panel G must be held closed. These relays must have contacts closed in order to close the generator output breakers using the Unit |
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600V Breakers BOP |
11BMC1, 11CMC1, 11BCMC
CP is 250 VDC
( step down transformer from each breaker)
11BCMC will auto close with a fault on TR 11BMC or TRCMC. NOT on associated bus. -sensing on high side of transformer and breaker will open. If High current clears, the fault is on the bus, and the bus remains dead. |
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Transformer Degradation |
Buildup of contaminants on insulators
grounds provide for clearance protection left unintentionally when a transformer is re-nergized.
Vibration
Symptoms: Hi-Hi Windings temperatures
Rapid power reduction to 50% power
Reactor trip oif temp not lowering
Severon alarms
Gas sampling and monitoring should recognize gassing before alarms come in when they are due to localized hot spots
Alarms could be due to general overheating if loss fo cooling were masked.
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How does the 11BCMC Auto Closure work? |
1) High current is sensed on transformer 2) Feed breaker to to fault opens (low side) 3) High Current Gone? -yes: Faulted Bus and no other action -no: Faulted Transformer then the following 4) Transformer feed breakers opens (high side) 5) Repeat signal to open bus feeder(low side) -11BCMC Closes to re-power bus Xfmr Dif(no time delay) Xfmrovercurrent (30 cycles) |
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RCP Bus Fast Transfer |
Automatic Re-alignment of power supplied to RCP buses from the UAT's to the RAT's.
Occurs when the generator lockout relays are actuated (either the Unit HEA or Overall HEA)
-Trip the generator output circuit breakers -Trip the UAT supply breakers to the RCP buses (About 5 cycles) -Close the RAT supply breakers to the RCP buses(About 7 Cycles)
These actions initiate simulatanously resulting in 30 milliseconds of dead time on RCP buses. Fast transfer is designed to maintain power to the RCP motors.
For lockout relay activated generator trips, the RCP buses immediately fast transfer. For reactor / turbine trips, there is a 30 second delay time while the generator reamins connected to the electrical system, then fast transfer intiates. |
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Preferred Offsite Power |
Train A is provided from 345 kV/765 kV Transformer 4 thru breaker BC/CD through the CD RAT.
Train B is provided from 345 kV Bus 1 Transformer 5 thru breaker BE/AB through the AB RAT.
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EP Motor Operated Disconnect |
69 kV Yard/EP/SDG - 48 VDC Distribution System
A loss of the 48V DC and Low Voltage AC Distribution System would eliminate control and protection of served components |
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4kV Breakers |
Control Power is from 250VDC from associated train battery
Loss of control power will prevent remote(eg. Control room or automatic _ breaker opening or closing |
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600V Breakers |
Control Power is provided by a stepdown 600V-200VAC transformer in each breaker. With power available to the breaker, control power is available. |
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Why do the Supplemental Diesel Generators must be placed in manual when EP power from the grid is used to supply 4kV safety busses? |
Prevents overloading the SDGS if power should be lost
-Loadshed is the only circuit which will open feed breakers, including EP feedbreaker, and load breakers. -If EP is being used to supply T-busses, it is likely that the EDG output breakers will be in Pull-To-Lock -Defeats load shed -If EP lost when load shed is defeated, then EP feed breakers and load breakers on T-Bus remain closed. IF The SDGs were allowed to remain in AUTO, an auto start and tie in to the 4kV EP bus would then tie them to the T Bus(es) and all closed load breakers. The SDGs would be overloaded. |
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How do you clear a fault condition on the Supplemental Diesel Generators? |
If an SDG has tripped(byfault) the fault condition must be cleared before the diesel can restart. -Local Action -Control Screen Action
Recognition of fault condition -SDG will have a shutdown fault alarm standing
Local Action - EMPCII + Panel - inside SDG enclosure -Local Engine C/S to Off/Reset -Wait 6 seconds -Local Engine C/S to Auto -Using the ALARM SUMMARY screen for the SDG concerned --SDG(1or2) General Shutdown Fault - Reset --SDG(1or2) Engine Status-Available
System Control Screen Action -SDG(1or2) C/S Icon to OFF/Reset -Wait 6 seconds -SDG(1or2) Engine C/S Icon to Auto
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What are the consequences of paralleling out of phase or with a significant voltage mismatch? |
Possible significant damage/fire to breaker, and associated bus ducts and wiring. |
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Describe the consequence of opening a disconnect under load. |
Disconnects are generally manually opened, although some of the EP disconnects have motor operators. Disconnects are never opened under load as the opening is oo slow and an arc will be drawn |
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What are conditions which can indicate transformer degradation? |
High Winding Temperature
Hydran Alarms |
